- At the Screening Visit, prior to the qualifying conjunctival allergen challenge, the subject must have an ocular symptom severity redness score of mild (<=1) prior to exposure to allergen. Following allergen challenge, the subject must achieve ocular itching and redness scores of at least moderate (>=2) in both eyes within 10 minutes of the last allergen challenge. For redness, the score must be >=2 in 2 of the 3 vessel beds. (details in section 8.2.6 and 8.3.2 of the protocol)